1. Field of the Invention
The present invention relates to a film deposition apparatus and a film deposition method for depositing a film on a substrate by carrying out plural cycles of supplying in turn at least two source gases to the substrate in order to form plural layers of a reaction product, and a storage medium storing a computer program for carrying out the film deposition method.
2. Description of the Related Art
Along with further reduction of pattern feature size in semiconductor devices, a better gap-filling capability in a gap-filling process where concave portions such as trenches formed in a semiconductor wafer are filled with the deposited film is being demanded. There has been known a gap-filling process where a thin film is deposited to fill a concave portion and the thin film is annealed in order to cause the thin film to reflow, so that a void formed in the as-deposited thin film in the concave portion is eliminated. However, the wafer needs to be heated for a relatively long time at a relatively high temperature in order to eliminate the void from the thin film that has once been deposited. Such an annealing process may limit production throughput and adversely affect a device structure formed before the annealing in terms of thermal history.
As another film deposition method except for the CVD method, there has been known a so-called Atomic Layer Deposition (ALD) or a Molecular Layer Deposition (MLD) in which at least two reaction gases are supplied to a wafer under vacuum to deposit a film on the wafer. This technique is advantageous in that the film thickness can be controlled at higher accuracy by the number of times of supplying in turn the gases, and in that the deposited film can have excellent uniformity over the wafer. In addition, because a reaction product is repeatedly deposited layer-by-layer in this film deposition method, a high density film can be obtained, and a conformal film that reflects a surface structure of an underlying layer can be obtained.
A film deposition apparatus suitable for carrying out the ALD method has been disclosed in Patent Documents 1 through 8, for example. Such a film deposition apparatus generally includes a vacuum chamber, a susceptor on which plural wafers are placed along a circumferential direction of the susceptor, the susceptor being provided in the vacuum chamber, and plural gas supplying portions that are provided in the vacuum chamber to oppose the susceptor and supply corresponding process gases (reaction gases).
The wafers W placed on the susceptor are heated and the susceptor is rotated in relation to the gas supplying portions. In addition, a first reaction gas and a second reaction gas are supplied to upper surfaces of the wafers from the corresponding gas supplying portions. The vacuum chamber is provided with a partition wall or an inert gas supplying portion for supplying an inert gas serving as a gas curtain in order to separate a process area where the first reaction gas is supplied and another process area where the second reaction gas is supplied.
As stated above, because the process areas are separated in order to impede the plural reaction gases from being intermixed with each other while the reaction gases are simultaneously supplied in a common vacuum chamber, the wafers are alternately exposed to the first reaction gas and the second reaction gas via the gas curtain or the partition wall. Therefore, the reaction gases supplied to the vacuum chamber need not to be switched, thereby carrying out the ALD method at high throughput.
Patent Document 9 describes a technology where water vapor is supplied after a silicon source gas and then an ozone gas is supplied in film deposition of a silicon oxide film by the ALD method.    Patent Document 1: U.S. Pat. No. 6,634,314    Patent Document 2: Japanese Patent Application Laid-Open Publication No. 2001-254181 (FIGS. 1, 2)    Patent Document 3: Japanese Patent Publication No. 3,144,664 (FIGS. 1, 2, claim 1)    Patent Document 4: Japanese Patent Application Laid-Open Publication No. H4-287912    Patent Document 5: U.S. Pat. No. 7,153,542 (FIGS. 8A, 8B)    Patent Document 6: Japanese Patent Application Laid-Open Publication No. 2007-247066 (paragraphs 0023 through 0025, 0058, FIGS. 12 and 13)    Patent Document 7: United States Patent Publication No. 2007/218701    Patent Document 8: United States Patent Publication No. 2007/218702    Patent Document 9: Japanese Patent Application Laid-Open Publication No. 2006-269621 (paragraph 0018, and FIG. 1)